Automatic telephone-exchange system



Aug., 7, i923.

L.. IPOLINKOWSIKY AUTOMATIC TELEPHONE EXCHANGE SYSTEM,

Filed Sept. lO 1919 2 Sheets-Sheet 1 INS m w m e H EAS A @La D A @S wAug. 7, w23. www@ L. POLINKOWSKY AUTOMATIC TELEPHONE EXCHANGE SYSTEMFiled Sept. l0, 1919 2 Sheets-Sheet 2 Pfg. ,2.

LPA POLJINKOWS'IKY, OF ANTWEJRP, BELGEUM, ASSIGNUEJ T0 EdTlEmlt MMWR/@COMPANY, INCORPORATED, 0F NEW] YURK, N. Y., A. CRPURMTIN. @F lmil.

AUTOMATIC TELEPHONE-EXCHANGE lm.

Application tiled September le, 191e. erial Ito. 322mm.

' To all whom t may concern.'

Be it known that l, Lira loLINitowsKr, a citizen of Russia, residing at1t llue du Bastion, Antwerp, Belgium, have invented certain new anduseful Improvements iii Automatic Telephone-Exchange Systems, ot' whichthe following is a full, clear, concise, and exact description.

'lhis invention relates to telephone systems and more particularly tosystems in which automatic switching apparatus is employed forestablishing talking connections between subscribers lines.

rl`he object of the invention is. to provide an arrangement whereby atalkin connection may be established between su scribers lines throughthe agency of a plurality oi didcrent types of automatic switchingapparatus. n

A feature of the invention consists in an arrangement of switching andcontrolling apparatus whereby a talhing connection between twosubscribers lines may be established in part by automatic selectiveswitches of the power-driven type and in part by automatic selectiveswitches of the step-byste type.

Jfurther feature relates to the provision; in a system involvingexchanges equipped with power-driven switches and exchanges vequippedwith step-'by-step switches, with interconnecting trunks between suchexchanges; of means operative when an interexchange call is made tocontrol the step-byr step switches in the called exchange forcompletingI the desired connection.

A still further feature consists in the provision, in a system where thepower-driven switches are arranged to be controlled by a register sendercontrolling mechanism, of means adapted .to cooperate with suchmechanism for the purpose of operating step-bystep switches to completethe establishment of a desired connection.

Other features and advantages of the present invention will becomeapparent from a consideration of the following description and theappended claims.

lin the accompanying drawings which illustrate a telephone systemembodying the.

novel features of this invention, Fig. l shows circuits and apparatus ina telephone exchange equipped with automatic switches of thepower-driven type. To the left ot' the broken line is shown asubscribers line incoming to the exchange and also a group selectorswitch adapted to extend such line in the establishment of connections.'llo the right of the breiten line there is shown the outgoing end'of atrunk circuit leading to a distant exchange together with circuits andapptaratus appertaining to said trunlt circui Fig. 2. shows an exchangeprovided with automaticswitches of the step-by-step type, the incomingend of said trunlt circuit terminating in a step-by-step selector to thelett of the broken line. To the right ot the broken line is shown thedetailed circuits ot a ste -by-step connector having access to callesubscribers lines. 3 shows a subscribers line terminating in theexchange at an operators position and also a switch, corresponding tothe one shown in Fig. 1, by means ot which the subscribers line may beextended to the outgoing trunk. According to this invention, a system isarranged in which subscribers to an exchange equipped with switches olithe powerdriven or continuous movement type are enabled to obtaintelephone connections with subscribers -lines terminatin in distantexchanges provided with switching apparatus of the step-by-ste type, aswell as with subscribers lines ocal to their own exchange. As is theusual practice in powerdrive systems, a calling subscriber, uponinitiatin a call, has his line automatically extende to a registercontrollin mechanism, incase oit a itull automatic system which hethereupon proceeds to set up in accordance with the designation ot thecalled line. ln case ot a semi-automatic system, the calling subscriberusually communicates the wanted number to an operator who, by means ot"the lreyboard, registers the desired number on the controllingmechanism. 'llhe controlling mechanism when thus positioned, operatesautomatically to control the selective operation of the switches tocomplete the extension of the calling line to the desired called line.lln the system shown, subscribers to the exchange are given facilitiesapart from those above outlined, whereby connections maybe extended totrunk lines leading to distant exchanges of the step-by-step type andthere further extended over step-by-step selector switches to the lineof a desired subscriber.

Whether the call is local or one to a ldistant step-by-step exchange,the register controlling mechanism is positioned either under thecontrol of the subscribers line directly or by means of an operatorskeyboard. In the event of an inter-exchange call, the controllingmechanism after having controlled the 0L eration of each selector switchto select an outgoing trunk line, continues in its operation inconjunction with apparatus associated with said trunk to cause theoperation of the step-by-step switches in the distant exchange.

In the drawings, it has not been considered necessary to give more thana detailed showing of a power-driven group selector switch and aregister controlling mechanism for controlling the operation thereof.This switch may be of any well-known construction in which a rotatablebrush carriage is adapted to be driven from a continuousIy operatingsource of power to drive its brushes over the terminals of connectingcircuits. The structure of such a switch is shown and described inpatent to McBerty No. 1,097,868 of May 26, 1914. The registercontrolling mechamsm is indicated briefly within the broken line in thelower lefthand corner of Fig. 1 and may comprise a plurality of sequenceswitch registers which, after having been adjusted from a callingsubscribers line or from an operators keyboard, are restored to theirnormal positions by means of a stepping relay in the wellknownfundamental circuit Ito perform the desired selective operation.Selective switches and a register controlling mechanism of the generalcharacter suitable for operation in the present system are shown anddescribed in detail in the patent to Polinkowsky No. 1,365,269, issuedJanuary 11,.

It is believed that a clearer understanding ma be had of the presentinvention by descrlbing in detail the establishment of a connection fromone subscribers line to another.

Assume that a subscriber to the line 100 in the power-driven exchangewishes to converse with the subscriber at line 200 terminating in adistant exchange equipped with step-by-step switches. lVhen thesubscriber at substation 100 removes his receiver' from the switchhook,his line is extended in the well-known manner through to the repeatingcoil 103 over conductors 101, 102 either by means of automatic finderswitches or by the agency of operators connecting switches such as shownin Fig. 3. If the system is of thefull automatic character, the callingsubscriber may then position the register controlling mechanism, showndiagrammatically at 150, whereas if the system is of the semi-automatictype, the operator, by means of her keyboard adjusts the registercontrolling mechanism in accordance with the designation received fromthe ceiling subscriber. When the register mechanism has been positioned,brush selection takes place in a well-known manner at the groupselector,

one set of brushes of which is shown at 107, 108, 109. For this purpose,the brush tripping spindle magnet 117 is energized in a circuitIincludinr contact and armature of relay 114. Rela 114 may be energizedin a circuit such as fo lows: Battery through the winding of said relay,contact 155 of a se uence switch individual to the group se ector,through the winding of stepping relay 116, ot' the register mechanism,contact/and armature of relay 115, contact 156 of the sequence switchbelonging to the register controlling mechanism to ground at contact113.. Magnet 117 causes the power-driven shaft 147 to be applied to thetripping spindle in the well-known manner. After brush selection hastaken place, the sequence switch of the group selector moves, as is wellunderstood, to an advanced position as, for example, position 5. Therelay 114 will become energlzed over a circuit including contacts 123and 124. The brush carriage power magnet 125 is now energized andoperatively associates the brush carriage with a continuously drivenmember 126. The circuit for the magnet 125 may be traced from batterthrough the winding of said magnet, bac contact and armature of relay119, contact 170, to ground at the contact and armature of relay 114.The brush carriage rotates to advance its brushes 107, 108, 109 over theterminals 110, 111, 112 of the selected level of trunks. In the caseassumed, these trunk lines lead to the distant step-by-step exchange.When the test brush 109 reaches the test terminal 112 of an idle trunk,a selectable potential bein found thereon. test relay 120 is energizeover the following circuit: battery 127, contact 135 (1) of sequenceswitch 130 individual to the trunk circuit, terminal 112, brush 109 toground through the left-hand high resistance winding of test relay 120.Relay 120 energizes and closes a low resistance path to ground throughits rigbt-hand windingr and the winding of relay 119. The relay 119, byattracting its armature, opens the power circuit of magnet 125 bringingto rest the brushes 107, 108, 109 on termmals 110, 111, 112. The lowresistance circuit to ground through relay 119 decreases the potentialon the multiples of terminals 112 so as to render the selected trunkbusy to other selector switches. In the well-known manner, the operationof relay 119 serves to drive the sequence switch (not shown) whichcontrols the circuits of the group selector switch into an advancedposition, such as position 6.

The fundamental circuit is now extended from the register mechanism 150to relay 121 at the outgoing end of the selected trunk ree-taco line.This circuit extends from battery through the winding of relay 121,contact 136 (1), terminal 111, brush 108, contact 106 (6) through thewinding of stepping relay 116, contact and armature of relay 115,contact 156, contact 105 (6), brush 107, terminal 110 to ground atcontact 137. Relays 121 and 116 energize, the relay 121 closing acircuit from ground over its lett-hand armature and front contact,contact 131 (1), through the winding ot sequence switch 130 to battery.Sequence switch 130 moves out ot position 1 and into position 2. Duringthe time sequence switch ,130 is passing from position 1 to position 2,its local contact 1.44 is closed to ground and relay 122 is energized inthe following circuit: from the free pole ot battery, contact 142,through the winding of relay 122, contact 141 to ground at local Contact144. Relay 122 is again deenergizcd as soon as the circuit just tracedopcns at contact 144 in position 2 ot sequence switch 130.

W hen sequence switch 130 reaches position 2, the outgoing end ot thetrunk line 151, 152 is closed and stepping relay 201 ot the firstselector 230 becomes energized. The circuit tor relay 201 is traceable`trom battery. through the right-hand winding thereof, back contact andinner lett-hand armature ot relay 228. conductor 151, conductor 153,contact 303 (1) of sequence switch 300, conductor 154, contact 143 (2)of sequence switch 130, conductor 152, outer left-hand armature and backcontact ot relay 223 through the lett-hand winding ot' relay 201 toground. Relay 201 attracts its armature and closes a circuit fromground, outer right-hand armature and contact ot relay 228, armature andfront contact ot relay 201, through the winding of slow-to-release relay202 to battery. Relay 202 operates and prepares aI circuit for thesecond slow-to-relcasc relay 203 and the primary stepping magnet 204. Atthe same time that sequence switch 130 reaches position 2, a circuit isclosed from battery through the winding ot' sequence switch 300, contact131 (2) to ground, at.. the trout contact and letthand armature of relay121. The local contact 304 of sequence switch 300 is so arranged thatsaid sequence switch is only permitted to stand at rest in position 1.When, therefore, sequence switch 300 is driven out ot position 1, itruns through a complete cycle of operation. rlhe. contact 303 otsequence switch 300 is closed in positions 1, 2. 3. and so on up toposition 10. rThe openings between these successive positions are sotaken in connection with the speed at which sequence switch 300 isdriven, that the trunk line. 151, 152 is intermittently opened andclosed by the Contact 303 in the saine manner thatl it would be openedand closed under the control of a substation transmitter. Furthermore,the contact 303 after having passed its tenth opening position and goesinto position 11, it remains closed thereafter thro-ugh to position 18.'rLhis comparatively long closed period ot contact 303 corresponds to theinterval in which a calling subscriber at a substation is adjusting hisdial tor the transmission ot the next seriesl and is 'designed to permitample time for the selective switch to com'- plete its trunk huntingoperation. When, therefore, sequence switch 300 asses out ot" position1, contact 303 opens t e circuit ot' stepping relay 201 at the firststep-by-step selector 230. Relay 201 retracting its armature, closes acircuit from ground,` outer right-hand armature and back contact ofrelay 228, armature and back Contact ot relaiy 201, inner armature andfront Contact o relay 202 through the windings of relay 203 and magnet204 to battery and ground. The primar stepping magnet 204 energizes inthe We l-known manner and steps the brushes 208, 209, 210 into operativerelation with the tirstlevel of trunk terminals. The sloW-to-releaserelay 203 also energizes in this circuit. When sequence switch contact303 reaches position 2, the trunk 151, 152 is closed and relay 201 opensthe circuit of magnet 204 Which deenergizes preparatory to advancing thebrushes ot the selector switch another step. 'llhe contact 302 ofsequence switch 300, also closed in position 2, completes theI followingalternate circ-uit tor relay 121: battery, through the winding oi rela121, contact 302 (2), contact 139 (2), bac contact and armature ot'relay 122, contact 140 (2) to ground. Relay 121 remains energized but.the circuit ljust traced shunts out the stepping relay 1.16 at thecontrolling mechanism 150. ln the manner well understood, the release ofrelay 116 prepares for the advance through another step ot a controllingregister u on which the hundreds designation of the called line isregistered. When sequence switch 300 leaves position 2, the trunkcircuit 151, 152 is opened a second time, relay 201 deenergizes and theprimary stepping magnet 204 operates to advance the selector brushes208, 209, 210 opposite the next level of trunks. Between positions 2 and3 ot' sequence switch 300, contact 302 opens to remove the shunt fromaround the stepping relay 116 in the fundamental circuit. Relay 116energizes and a controlling register of the mechanism 150 advancesanother step. ln position 3 of sequence switch 300, contact 303 closesto again cause the deenergzation of stepping magnet 204 and contact 302shortcircuits stepping relay 116 causing this relay to deencrgize. Thisopera-tion continues until the controlling register of the mechanism 150reaches its normal position at which time relay. 115 energizes in aWelL- "lol known manner to open the fundamental circuit. As soon afterthis occurrenceJ as contact 302 of sequence switch 300 is again opened,the relay 121 deenergizes. The retraction of thelcft-hand armature ofrela 121 closes a circuit including contact 132 (2 to drive the sequenceswitch 130 out of position 2 and into position 3. The sequence switchcontact 303 has thus opened and closed the trunk circuit 151, 152 anumber of times corresponding to the setting of the controllingmechanism 150 and primary stepping magnet 204 has advanced the brushes208, 209 and 210 to the proper level of trunks leading to connectorswitches such as 240. Dependent upon the size of the digit, the sequenceswitch 300 will be in one of its positions between position 1 andposition 11., at the time the fundamental circuit is opened and sequenceswitch 130 goes into position 3. If the digit be less t-han ten,seouence switch 300 will not have reached position 11. To insure thatcontact 303 cannot open the trunk circuit to falsely operate thestepping magnet 204 during the time sequence. switch 300 is reachingposition 11, the trunk circuit is maintained closed by a substitutecircuit and stepping relay 201 is held energized. This circuit for relay201 mayl be traced from battery through the right-hand winding thereof,back contact and inner left-hand armature of relay 228, conductors 151and 153, contact 133 (3). right-hand armature and-back contact of relay121, conductor 154, cont-act 143 (3) conductor 152, outer left-handarmature, and back contact of relay 228 through the lefthand winding ofrelay 201 to ground. The sequence switch 300 continues to run throughthe remainder of its cycle under the control of local contact 304.

On the first primary step of the selector switch 230, the primaryoff-normal contacts 229 and 231 are closed. Relay 206 energizes in acircuit from battery through the winding of said relay, contact 229,front contact and armature of relay 203 to ground at the front contactand outer armature of relay 202. When relay 201 attracts its armaturepermanently after the completion of the primary movement,slow-to-release relay 203 deenergizes after the elapse of an interval oftime. The deenergization of relay 203 closes a circuit from battery,through the winding of the secondary stepping magnet 205, righthandarmature and contact of relay 206, back contact and armature of relay203 to ground at the contactl and outer armature of relay 202. Therelease of the armature of relay 203 opens at the same time the circuit4traced for relay 206, but relay 206 does not release its armatures untilafter the steping magnet 205 has had time to operate. hile the initialoperating circuit of relay 206 is opened upon the release of relay 203,

a substitute circuit exists for relay 206 as follows: battery, throughthe winding of said relay, ofi' normal contact 229, left contact ofmagnet 205, Winding of relay 228 to ground at the contact and outerarmature of relay,202. The resistance of relay 228 is comparativelyhigh, such that the relay 206 cannot operate when placed in series .withrelay 228, as will be seen hereinafter. Moreover, the relay 206, ifoperated, and then included in series with relay 228, cannot maintainits armatures attracted. In the latter case, however, the relay 206,although normally a quick operating relay, releases gradually since therelay 228 permits a certain amount of current to flow. Hence, While therelay 206 is holding its armatures attracted for an interval followingthe release of relay 203, the above traced circuit is completed for thesecondary Steppin magnet 205. The magnet 205 operates an advances thebrushes 208, 209, 210 on to the first set of terminals in the selectedlevel of trunks. Relay 206 now releases its armatures and opens the enerizing circuit of stcppmg magnet 205. I the first trunk leads to aconnector switchl which is busy, ground will be found on the testterminal 213 thereof and relay 206 becomes energized in a circuit frombattery, through the winding of said relay, contact 229, contact andouter armature of stepping magnet 205, back contact and inner armatureof relay 228, test brush 210, terminal 213 to ground at the frontcontact and left-hand armature of relay 215. Relay 206, by attractingits armature, closes an operating circuit of stepping magnet 205 andbrushes 208, 209 and 210 are advanced through a second step. Theoperation of the stepping magnet 205 now opens the circuit of relay 206which deenergizes and by releasing its right-hand armature opens thecircuit of magnet 205 causing s aid magnet to also deenergize. T hismethod of operation proceeds until the test brush l210 reaches anungrounded terminal 213. Relay 206 then remains deenergized and thebrushes 208, 209 and -210 are brought to rest with terminals 211, 212and 213 of a trunk leading to an idle connector switch 240. During thetrunk hunting operation and while test brush 210 is continually inengagement with grounded terminal 213, the circuit from battery throughrelay 206, contact 229 and contact and outer armature of magnet 205leads directly' to ground over the back contact and inner right-handarmature of relay 228 and test brush 210. As soon as an idle trunk isfound, however, upon the terminal 213 of which no ground exists, thecircuit through relay 206 may be traced to ground in the followingmanner: battery through the winding of relay 206 contact 229, contactand outer armatum o magnet 205 through the winding of relay 228 dit itil

Vswitch arm 222 (position 1) to incarna y A' i to ground at the contactand outer armature of rela 202. Relay 228, being no longershortcircuited loy a. circuit to ground over test brush 210 becomesenergized. The re lay 228 and relay 206 are so adjusted that relay 228will energize whereas relay 206 does not energize in series with relay228.

lltelay 228 opens the circuit of stepping relay 201 and entends thetrunlr conductors 151, 152 through to the connector switch 210. Steppinrelay 211 now'energizes in a circuit from attery through the left-handwinding thereof, terminal 211, brush 208, iirontcontact and innerlett-hand armature oit relay 228, conductors 151 and 153 to conductor151 either over sequence switch contact 303er se uence switch Contact133 and the right-han armature and hach contact ot relay 121 thencereturning by contact 113z conductor 152, outer lett-hand armature otrelay 128, brush 209, terminal 212 through the right-hand winding ofrelay 211, side ound. litelay 211 closes a circuit over its armature andfront contact tor the energization ot slcw-to-release relay 215. rli`lierelay 215, at its lett-hand ,armature and iront contact, places a busyground upon the multiples et terminals 213 to render the connectorswitch 210 non-selectable to other selector switches. At the time therelay 201 released its armature, it opened the circuit for relay 202which, in turn, opened the original energizing circuit of relay 228.rlhe relay 202, however, being sluggish in releasin does not sever thecircuit of relay 228 until after the slow-tc-release relay 215 at theconnector switch is energized. Therefore, the relay 228 is maintainedoperated in a circuit troni battery through the winding of relay 206,contact 229, contact and outer armature ot magnet 205 through theWinding of relay 228, front contact and inner armature ot relay 228,brush 210, terminal 213 to ground at the liront contact and lett-handarmature of relay 215. Relay 215 also prepares a stepping circuit forthe primary magnet 217 in series with a second slow-to-release relay216.

'W hen sequence switch 300 reaches its normal position 1, sequenceswitch 130 is driven from position 3 into position 1 by means of acircuit including contact 132 (3) and contact 301 (1) of sequence switch300. The apparatus is now in condition to control the primary selectingoperation of the connector switch 210. The fundamental circuit is againclosed and relays 121, 116 are both en ergized. llielay 121 closes acircuit trom battery through the winding of sequence switch 300, Contact131 (1) to ground at the iront contact and left-hand amature of relay121. Sequence switch 300 thereupon leaves sition 1 and under the controlot its loca contact 301 runs through a coinplete cycle of operation.When contact 303' leaves position 1,the trunk 151, 152 ie ened andstepping relay 211 is energized. -elay 211 closes a circuit frombattery, side switch arm 221 (position 1) through the windings ofprimary ste ping magnet 217 and relay 216, Contact an right-handarmature of relay 215 to ground at the back oontact and armature otrelay 211. rll`he primary stepping magnet 217 operates in the well-knownmanner to advance theffbrushes 232, 233 and 231 of the connector switchinto operative relation with the first level of line terminals. Theslow-to-release relay 216 also energizes and closes a circuit for theescape magnet 219. lin position 2 ofscquence switch 300, contact 303closes the trunk circuit 151, 152, relay 211 ener 'zes and steppingmagnet 217 deenergizes. ontact 302 in position 2 of sequence switch 300short-circuits the stepping relay 116 above described and the tensregister at the controlling mechanism 150 is prepared to adyance throughanother position. 0n leaving position 2, sequence switch 300 once moreopens the trunk circuit 151, 152, relay 211 deenergizes and the steppingmagnet 217 operates a second time to advance brushes 232, 233- and 231into operative relation with the second level ot' line terminals.llielays 215 and 216 being slow to release `maintain their armaturesAattracted during the interruptions ot the trunlr circuit. After theregister controlling mecha nism 150 is operated in accordance with theregistration of the tens digit, relay 115 opens the fundamental circuitand upon the neat opening of contact 202, relay 121 is deenergized.Relay 121 closes a circuit includin its left-hand armature and backcontact an contact 132 to drive sequence switch 130 into position 5.'llhe trunk circuit 151, 152 is again closed at the right-hand armatureand back contact of relay 121 independent of Contact 303 and maintainsstepping relay 211 energized during thev time the sequence switch 300 isrunning throii h its remaining positions to position 1. elay 211 beingenergized for a sufficient period causes the deenergization otslow-to-release relay 216. Relay 216 opens the circuit of the escapemagnet 210 which deenergizes and releases the side switch into itssecond position.

Upon sequence switch 300 reaching its position 1, a circuit is closedfrom battery through the winding of se uence switch 130, contact 132 (5)to groun at contacts 301. Sequence switch 130 moves into position 6. Thefundamental circuit is closed again in the usual manner and relays 121and 116 energize. Relay 121 closes a circuit from ground ovler itsleft-hand armature and front contact and contact 131 (6) to drive thesequence switch 300 out ot position 1. Sequence switch 300 completes itsnal llllii cycle of operation under the control of. its local contact304. In the manner similar to that already described, the contact 303causes the opening and closure of trunk 151, 152 tov cause the operationof relay 214 in accordance with the units digit. At the first retractionof the armature of relay 214, a circuit'is closed from ground, armatureand back contact of said relay, right-hand armature and contact of relay215 through the winding of relay 216, contact and le thand armature ofrelay 223 through the winding of the secondary stepping magnet 218, sideswitch arm 221 (position 2), to battery and ground. The stepping magnet218 operates to advance the brushes 232, 233

and 234 onto the first set of terminals in the selected level. Relay 216energlzes in the circuit traced and again closes an energizing circuitfor the escape magnet 219. For each succeeding retraction of thearmature of relay 214, the brushes 232, 233 and 234 are advanced overone set of terminals and linall come to rest in contact withthe terminas of the called line. When the last impulse has been sent and relay 121deenergizes, sequence switch 130 is driven into position 10 by means ofa circuit including contact 132 (6) and thel back contact and left-handarmature of relay 121.

When sequence switch 130 passes through position 7%, relay 121 isenergized in a circuit from battery through the winding of said relay,contact 135, terminal 112, brush 109to ground through the highresistance winding of relay 120. Relay 121 closes a locking circuit foritself including contact 134, front contact and right-hand armature ofrelay 121, contact 133 and resistance 128, The rela 120 does notenergize in this circuit. n position 10 of sequence switch 130, acircuit is established from battery, through the lower right-handwinding of repeating coil 103, winding of supervisory relay 104, contact106, brush 108, terminal 111 to ground at Contact 136. Supervisory relay104 therefore becomes energized. As soon as sequence switch 130 reachesposition 7, relay 122 energizes in a circuit from battery through thelefthand winding of relay 214, terminal 211, brush 208, front contactand inner lefthand armature Vof relay 228, conductor 151, Contact 142,through the winding of relay 122, contact 141, conductor 152, outerlefthand armature and front contact of relay 228., `brush 209, terminal212 through the right-hand winding of relay 214, side switch arm 222(position 2) to ground. After'the last impulse of the units seres hasbeen sent, relay 214 holds its armature attracted for an interval oftime suflicient to permit the deenergization of slow-to-release relay216. If the called line 200 is idle, no ground potential exists on testterminal 235 and when relay 216 deenergizes, the escape ma et 219releases the side switch into its t ird position. Relay 226 operates ina circuit from battery over side switch arm 221 (position 3) through theWinding of relay 226 to ground at side switch arm 227 (position 3).Relay 226 closes a locking circuit through to the called line. Thiscircuit may be traced from the ringing source 236 and back contact andouter right-hand armature of relay 225, lower armature and contact ofrelay 226, brush 233, over the loop of the called line 200 and returningby way of brush 232, contact and upper armature of relay 226, innerright-hand armature and back contact of relay 225 through the lrighthandwinding of relay 225 to battery and ground. Relay 225 does not energizewhile ringing current is being applied to the line.

When the side switch at the connector 240 goes into position 3 toprepare for the -application of ringing current to the called line, sideswitch arm 222 includes a resistance 238 in series with the right-handwinding of relay 214 and relay 122 at the outgoing end of the trunk 151,152. Relay 122 being unable to remain energized in series with theresistance 238, releases its armature and establishes a circuit fordriving sequence switch 130 out of position 10 and into position 13.This circuit may be followed from battery through the winding of saidsequence switch, contact 139 (10), back/contact and armature of relay122 to grou/nd at contact 140. In position 13, the circuit for thesupervisory relay 104 is opened at contact 136. Supervisory relay 104deenergizes and may in any well-known manner operate a supervisorysignal to inform an operator that ringing current is being placed uponthe called line.

When the called subscriber answers, the resistance of the circuit forthe right-hand -winding of relay 225 is reduced sufiiciently to permitsaid relay to energize. At its left-hand armature,this relay closes alocking circuit for itself to ground at the offnormal contact 237. Atits right-hand armatures, the relay 2,25 closes the following circuitfor the called line relay 224: battery through the left-hand winding ofrelay 224, front contact and inner right-hand armature of relay 225,upper armature and contact of relay 226, brush 232 over the loop of thecalled line, brush 233, contact and lower armature of relay 226, outerright-hand armature and front contact of relay 225. righthand winding ofrelay 224` left-hand armature and contact of relay 225, to ground at theoil-normal contact 237. Talking battery is supplied to the called linethrough the windings of the relay 224. Relay 224 attracts its armatureand shunts out the resisttiti raearoa ance 238 so that relay 122 isagain permitted to attract its armature. Relay 122 closes a circuit fromground, contact `140, armature and front contact of rela 122, contact138 (13) through the win ing of sequence switch 130 to battery. Sequenceswitch 130 thereupon advances into position 14. ln position 14 ofsequence switch 130, a circuit is established from battery through thelower right-hand winding of the repeating coil 103, winding ofsupervisory relay 104, contact 106, brush 108, terminal 111 through theimpedance 146, contact'140 (14) armature and front contact of relay 122,contact 138 (14), contact 137 (14) terminal 110, brush 107, contact 105through the upper right-hand winding of repeating coil 103 to ground.Supervisory -relay 104 energizes and in any well-known manner may serveto operate a supervisory, signal before an operator to indicate that thecalled subscriber has responded.

At the termination of' the conversation, the called subscriber replaceshis receiver on the switchhook causing' the deenergization of relay 224.Relay 224, by releasing its armature, causes the resistance 238 to againbe included in series with the relay 122. Relay 122 thereforedeenergizes and opens the circuit for the supervisory relay 104. Relay104, by deenergiz'lng, may serve to display a signal before the operatorindicating that the called subscribern has hung up his receiver. lincase of a full automatic system, the relay 104 may operate to initiatethe release of the selector switch.` ln either case, as soon as thepower-driven selector switch restores and brush 109 disengages theterminal 112, the relay 121 becomes deenergized. A circuit is now closedincluding the left-hand armature and back contact of relay 121 andcontact 132 to drive sequence switch 130 out of position 14 and into position 1. Sequence switch 130 in passing out of position 14 opens atcontacts 141 and 142, the circuit of the calling line relay 214. Relay214 releases and after an interval, relay 215 deenergizes'. Relay 215 atits lefthand armature and back contact closes a circuit includingoff-normal contact 239 for the release magnet 220. Magnet 220 operatesto release the connector switch 240. Relay 215 at its left-hand armatureand front contact opens the holding circuit for relay 228 at theselector switch 230. Upon the retraction of the outer right-handarmature of relay 228, a circuit is closed including the armature andback contact of relay 201, inner armature and back contact of relay 202,primary off-normal contact 231 and the winding of release magnet 207.-Magnet 207 energizes in this circuit and restores the selector switch230 to its normal position. The apparatus has now been completelyreturned to normal and may be taken for use in connection withsubsequent calls.

Assume that the called line 200 is found to be engaged. lin thisinstance, a ground potential will be found on the multiples of testterminals 235 which ground may be supplied, for example, over a sideswitch arm 227 of some other connector switch standing in its thirdposition. At the termination of the units series of impulses, relay 216releases its armature after an interval. The escape magnet 219 however,is maintained energized by means of the following substitute circuit:battery through the winding of said escape magnet, makebefore-breakcontact of relay 216, through the winding of relay 223, normal contactof said relay, side switch arm 227 (position 2), brush 234, and terminal235 to ground. Belay 223 energizes and locks up in a circuit includingits right-hand make-before-brealr. contact and oil-normal contact 237.'.lhe escape magnet 219 by remaining energized prevents the side switchfrom advancing into position 3. armature of-relay 223, a busy tone fromthe coil B2 is supplied to the calling line to notify the callingsubscriber that the desired line is busy. The calling subscriber byreplacing his receiver upon the switchhook either gives a disconnectsignal to an operator or automatically causes the release of theswitches in the first exchange. 'llhe release of the step-by-stepswitches in the second exchange and of the remaining apparatus takesplace as above described.

What is claimed is: A

1. ln a telephone exchange system, a calling line, a called line, anumerically operated switch arranged to be driven in a continuousmovement, step-by-step switches, means for operating said firstmentioned switch in its continuous movement to extend the calling line,and means for operating said step-by-step switches to further extend thecalling line into connection with said called line.

2. ln a telephone exchange system, a calling line, a called line, aselective switch arranged to he driven in a continuous movement,stcp-by-step switches, a sender for controlling the 'operation of saidselective switch in its continuous movement to extend the calling line,and means controlled by said sender for operating said step-by-stepswitches to further extend the calling line into connection with saidcalled line. i

3. ln a telephone exchange system, a calling line, a called line. aselective switch a1'- ranged to be driven in a continuous movement,step-by-step switches. a sender for controlling the operation of saidselective switch in its continuous movement to extend the calling line,and means arranged to At the outer righthand vunder the control of saidsender for operating said step-by-step switches to further extend thecalling line into connection with said called line.

5. In a telephone exchange systemz a calling line, a called line, aselective switch arranged to be driven in a continuous movement, a trunkline. step-by-step switches, a

sender for controlling the selective operation of said selective switchto extend the calling line to said trunk, and means associated with saidtrunk and arranged to cooperate with said sender for operating saidstep-by-step switches to further extend the calling line into connectionwith said called line.

6. In a telephone exchange system, a calling line, a called line, aselective switch arranged to be driven in a continuous movement,step-by-step switches, a trunk line extending in the direction of s aidlatter switches, a sender for` controlling the selective operation ofsaid selective switch to extend the calling line to said trunk, and asequence switch associated with said trunk and arranged to cooperatewith said sender for operating said step-by-step switches to furtherextend the calling line into connection with said called line.

7. In a telephone exchange system, a calling line, a calledfline, aselective switch arranged tobe driven in a continuous movement, a seriesof step-by-step switches a sender for controlling the selectiveoperation of said selective switch to extend the calling line, and anauxiliary switch arranged to be driven through a plurality of cycles ofoperation under the control-of said sender for causing the successiveoperation of said step-by-step switches to further extend the callingline into connection with said called line.

8. In a telephone system, a calling line, a called line, a selectiveswitch arranged to be driven in a continuous movement, step-bystepswitches, a trunk line extending in the direction of said step-by-stepswitches, means for operating said selective switch in its continuousmovement to extend the calling line to said trunk, means associated withsaid trunk for sending impulses thereover, and means responsive to saidimpulses for operating the step-by-step switches to further extend thecalling line into connection with said called line.

9. In a telephone system, a calling line, a called line, a selectiveswitch arranged to be driven in a continuous movement, a trunk line, astep-by-step switch 'in which said trunk line terminates, a sender,means controlled by said sender for operating said selective switch toextend the calling line to said trunk, means associated with said trunkand under the control of said sender for sending impulses over saidtrunk, and means res onsive to said impulses for operating saidstep-by-step switch to further extend the calling line in the directionof said called line.

10. In a telephone system, a calling line, a

called line, a selective switch arranged toV be driven in a continuousmovement, a trunk line, a step-by-step switch in which said trunkterminates, a continuously operating source of power for driving saidselective switch in itsy continuous movement to extend the' calling lineto said trunk, and means for operating said step-by-step switch tofurther extend the calling line in the direction of said called line.

11. In a telephone system, a line, a selectivc switch, a second switcharranged to be operated in an interrupted movement, means for operatingsaid selective switch in a continuous uninterrupted movement to its setposition to extend said line to the second switch, and means foroperating said second switch to further extend said line.

12. In a telephone system, a calling line, a sender means lfortransmitting impulses over said line to operate said sender to establishthe record of a designation thereon, a step-by-step switch, and meanscontrolled by said sender for sending impulses to operate thestep-by-step switch to extend said line in a talking connection.

13. In a telephone exchange system. a calling line, anumerically-operated switch arranged to be driven in a continuousmovement, a step-by-step switch, means for operating said first switchin its continuous movement to extend the calling line, and means foroperating said step-by-step switch to extend the calling line.

111. In a telephone exchange system, a calling line, anumerically-operated switch arranged to be driven in a continuousmovement, a step-by-step switch, means for operating saidfirst-mentioned switch in its continuous movement to extend the callingline, and means for directively operating said step-by-step switch tofurther extend the calling line.

In witness whereof. I hereunto subscribe my name this 13th day of AugustA. D.,

LIPA POLINKO-WSKY.

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